JP2011108982A - Solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell module in which a crack can be prevented from occurring in connecting a wiring member by considering an error caused by an apparatus and reducing a shear stress applied on a solar cell and an yield of the module is enhanced. <P>SOLUTION: In a solar cell module including a front-side protective member, a back-side protective member, and a plurality of solar cells connected to each other through a tab between the front-side protective member and the back-side protective member, a solar cell 1 has a plurality of front-side finger electrodes 110 and a bus bar electrode 111 which are arranged on the light receiving side and connected with a tab, as well as a plurality of back-side finger electrodes 120 and a bus bar electrode 121 which are arranged on the back-side and connected with a tab. The bus bar electrode 121 is alternately disposed so that a protrusion 121a and a recess 121b are neither linked to each other nor superposed to the bus bar electrode 111 and they have a predetermined distance therebetween. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solar cell module, and more particularly to a solar cell module including a plurality of solar cells connected to each other by connecting electrodes formed on the surface of adjacent solar cells with a wiring member.

  In the solar cell module, electrodes of a plurality of solar cells are electrically connected to each other by a wiring member made of a conductive member such as a copper foil, and a transparent surface protecting member such as glass or translucent plastic, PET Between the back protective material which consists of films, such as (Poly Ethylene Terphate), it is sealed with the sealing material which has translucency, such as EVA (Ethylene Vinyl Acetic acid).

  The electrodes of the solar cell are formed in a comb shape having a plurality of finger electrodes and bus bar electrodes using conductive paste on the front and back surfaces. A plurality of solar cells are connected in series by connecting a wiring member on the bus bar electrode provided on the surface of one solar cell and on the bus bar electrode provided on the back surface of the other solar cell. . Conventionally, solder is used to connect the bus bar electrode of the solar cell and the wiring member when the solar cell module is manufactured. Solder is widely used because it is excellent in connection reliability such as electrical conductivity and fixing strength, is inexpensive and versatile.

  On the other hand, from the viewpoint of environmental protection, a wiring connection method that does not use solder in a solar cell is also used. For example, a method of connecting a solar cell and a wiring material using an adhesive film having a resin adhesive is known (see, for example, Patent Document 1).

  Wiring connection using an adhesive film is performed by first attaching the adhesive film on the bus bar electrode of the solar cell, placing the wiring member on the adhesive film, and heating the wiring member while pressing it in the direction of the solar cell. The wiring member is connected to the bus bar electrode of the solar cell by the resin adhesive. As the shape of the bus bar electrode, in addition to a strip shape corresponding to the width of the wiring member, a linear electrode that is folded back in the width direction of the wiring member is known (see, for example, FIG. 6 of Patent Document 2).

  By the way, in order to reduce the cost and resource of the solar cell, it is required to make the solar cell thinner.

  As described above, in the method of connecting the wiring members with the resin adhesive, the wiring members are pressurized in the solar cell direction. Part of the pressure at this time is transmitted to the solar cell through the bus bar electrode. In particular, if the position of the bus bar electrode formed on the light receiving surface of the solar cell and the bus bar electrode formed on the back surface do not match, a shear stress is applied to the substrate of the solar cell, and a crack or the like is generated in the substrate. There is a problem that the yield decreases. In particular, as the solar cell becomes thinner, it becomes important to deal with shear stress.

JP 2007-214533 A Japanese Patent Laid-Open No. 2008-135552

  As shown in FIG. 13, it is ideal that the bus bar electrode 111 disposed on the light receiving surface side of the solar cell 1 and the bus bar electrode 121 disposed on the back surface side coincide with each other. In the state where the positions of the bus bar electrode 111 and the bus bar electrode 121 coincide with each other, a resin adhesive film (not shown) is disposed between the wiring member 20 and the bus bar electrodes 111 and 121, respectively, as indicated by the arrows in the drawing, The wiring member 20 is pressurized in the direction of the solar cell 1. As shown in FIG. 12, when the positions of the bus bar electrode 111 and the bus bar electrode 121 are completely coincident, the shearing force is suppressed from being applied to the solar cell 1, and the generation of cracks in the solar cell 1 is suppressed. The

  However, when an apparatus error is considered, as shown in FIG. 11, the front-side bus bar electrode 111 and the rear-side bus bar electrode 121 may be misaligned due to printing misalignment. Note that FIG. 11 shows a finger electrode 120 on the back side formed integrally with the bus bar electrode 121.

  As shown in FIGS. 11 and 13, when the positions of the bus bar electrode 111 and the bus bar electrode 121 are shifted, the solar cell 1 sandwiched between the bus bar electrode 111 and the bus bar electrode 121 is connected when the wiring member 20 is connected. Shear stress is applied as shown by the broken line arrows in the figure. Due to this shear stress, cracks are generated in the worst case, and there is a problem that the yield is lowered.

  The present invention has been made in view of the above-described conventional circumstances, considers the error of the device, reduces the shear stress applied to the solar cell, can suppress the generation of cracks when connecting the wiring members, and can improve the yield. It is an object of the present invention to provide a solar cell module that can be improved.

  This invention is a solar cell module comprising a front surface side protection member, a back surface side protection member, and a plurality of solar cells connected to each other by a wiring member between the front surface side protection member and the back surface side protection member. The solar cell is provided on a light receiving surface, and is connected to the wiring member with a plurality of front surface side finger electrodes and bus bar electrodes, and is provided on the back surface with a plurality of back surface side finger electrodes connected to the wiring member and One of the bus bar electrodes is alternately arranged so that the crests and the troughs are not connected to each other and do not overlap with the other bus bar electrode and at a predetermined interval. It is characterized by that.

  Further, the back-side bus bar electrode is configured so that the crests and troughs are alternately connected to each other within a range determined in consideration of mechanical errors with respect to the front-side bus bar electrode. do it.

  Furthermore, it is good to provide the connection part which connects the said peak part and trough part in a part of said finger electrode. The connecting portion may be formed wider than the finger electrode.

  According to the present invention, the crests and the troughs are alternately arranged without being connected to each other, so that the front side bus bar electrode and the back side bus bar electrode are arranged with a predetermined interval without overlapping. Thus, the concentration of the shear stress due to the pressurization at the time of connecting the wiring members is eliminated, the generation of cracks and the like of the solar cell can be suppressed, and the yield can be improved.

It is a top view of the solar cell in the solar cell module concerning embodiment of this invention. FIG. 2 is a cross-sectional view taken along line A-A ′ in FIG. 1. It is a top view which shows the solar cell in the solar cell module concerning 1st Embodiment of this invention, (a) is a light-receiving surface (front surface) side, (b) is seen from the back surface side. It is a top view which shows the principal part of the solar cell in the solar cell module concerning 1st Embodiment of this invention. FIG. 2 is a cross-sectional view showing the solar cell module according to the first embodiment of the present invention and enlarging the main part of the cross section along line B-B ′ of FIG. 1. It is a top view which shows the solar cell in the solar cell module concerning 2nd Embodiment of this invention, (a) is the light-receiving surface (front surface) side, (b) is seen from the back surface side. It is a top view which shows the principal part of the solar cell in the solar cell module concerning 2nd Embodiment of this invention. FIG. 5 is a cross-sectional view showing a solar cell module according to a second embodiment of the present invention, in which the main part of the cross section along line B-B ′ of FIG. 1 is enlarged. It is a schematic sectional drawing of the solar cell module of this invention. It is a schematic diagram which shows the connection process of the tab of the solar cell module of this invention. It is a top view which shows the position shift state of the bus-bar electrode part of the solar cell in the conventional solar cell module. It is a schematic diagram which shows the connection process of the tab of the conventional solar cell module. It is a schematic diagram which shows the connection process of the tab of the conventional solar cell module.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated in order to avoid duplication of description.

  A solar cell module according to a first embodiment of the present invention will be described with reference to FIGS.

  This solar cell module includes a plurality of plate-like solar cells 1. The solar cell 1 is made of, for example, a crystalline semiconductor composed of single crystal silicon or polycrystalline silicon having a thickness of about 0.15 mm, and has a substantially square shape having a side of about 125 mm, but is not limited thereto. Alternatively, other solar cells may be used.

  In the solar cell 1, for example, an n-type region and a p-type region are formed, and a junction for forming an electric field for carrier separation is formed at an interface portion between the n-type region and the p-type region. . The n-type region and the p-type region are composed of a crystalline semiconductor such as single crystal silicon or polycrystalline silicon, a compound semiconductor such as GaAs or InP, a thin film semiconductor such as a thin film Si or CuInSe having an amorphous state or a microcrystalline state, or the like. Semiconductors used for solar cells can be formed singly or in combination. As an example, a thin intrinsic amorphous silicon layer is inserted between single crystal silicon and amorphous silicon layers having opposite conductivity types to reduce defects at the interface and improve the characteristics of the heterojunction interface. The so-called HIT structure solar cell is used.

  A surface electrode 11 is formed on the surface portion of the solar cell 1 on the light receiving surface (front surface) side. The surface electrode 11 includes a plurality of finger electrodes 110 formed in parallel to each other. For example, about 55 finger electrodes 110 with a finger electrode width of 100 μm, a pitch of 2 mm, and an electrode thickness of 50 μm are formed. A tab 20 as a wiring member is connected orthogonally to the finger electrode 110.

  As shown in FIGS. 3 and 4, the surface electrode 11 is provided with a polygonal bus bar electrode 111 in accordance with the position where the tab is connected. The bus bar electrode 111 is provided based on the following conditions.

  That is, assuming that the error in the tab attachment position due to mechanical accuracy is x, the width of the tab 20 is a, and the width interval of the broken lines of the bus bar electrodes 111 is b, the relationship of b = a + 2 × | x | is satisfied. In this way, a polygonal bus bar electrode 111 is formed. For example, when the width a of the tab 20 is 1.2 mm, the sum of the error of the tab attachment position and the error of the bus bar electrode due to the mechanical accuracy is ± 0.2 mm. The bus bar electrodes 111 having a width equal to or larger than the finger electrodes 110 and having the same thickness as the finger electrodes 110 are arranged at intervals of 6 mm (b in the drawing).

  The bus bar electrode 111 is disposed within a range in consideration of the mechanical error of the tab 20 indicated by the one-dot chain line in FIG. That is, it extends diagonally from the center position in the left direction in the figure and reaches a left side of 0.8 mm, then it is bent diagonally in the right direction and extends from the left end to the right end to a position of 1.6 mm. The bus bar electrode 111 is formed in a polygonal line shape so as to bend in the left direction when reaching the right end, and in the tab attaching direction. In this embodiment, three bus bar electrodes 111 are provided.

  The surface electrode 11 including the finger electrode 110 and the bus bar electrode 111 is formed by, for example, screen printing a silver paste and curing it at a temperature of a few hundred degrees.

  Further, a back electrode 12 is formed on the front surface portion of the solar cell 1. The back electrode 12 includes a plurality of finger electrodes 120 formed in parallel to each other. For example, about 217 finger electrodes 120 having a finger electrode width of 100 μm, a pitch of 0.5 mm, and an electrode thickness of 10 μm are formed.

  In this embodiment, as shown in FIG. 3, the number of finger electrodes 120 of the back surface electrode 12 is made larger than the number of finger electrodes 110 of the front surface electrode 11.

  Further, a bus bar electrode 121 is also provided on the back electrode 12. In this embodiment, the front-side bus bar electrode 111 and the back-side bus bar electrode 121 do not overlap each other, and the positional relationship between the two does not cause a large shear stress even when a positional shift occurs during the formation of both. Are formed so as to be separated by a predetermined range.

  For this reason, as shown in FIG. 4, the rear surface side bus bar electrode 121 is provided with a predetermined distance from the front surface side bus bar electrode 111. Then, by simply arranging them at a predetermined interval, as shown by a peak 121a 'in FIG. 4, there are places that deviate greatly from the range (b in the figure) in which the mechanical error of the tab 20 is considered. To do. Therefore, in this embodiment, the bus bar electrode 111 on the front surface side and the bus bar electrode 121 on the back surface side are shifted from each other by an interval of b / 2, and half the length of each line segment of the broken line bus bar electrode 111 on the front surface side. The valley part 121b and the mountain part 121a which are bent at this time are configured. The crests 121a and the troughs 121b are alternately connected to the front-side bus bar electrode 111 so that the back-side bus bar electrode 121 is disposed within a range b determined in consideration of mechanical errors. Arranged without.

  As shown in FIG. 4, the range extending from the upper end in the drawing (b in the drawing) to the center position in the drawing diagonally to the right in the drawing in the range (b in the drawing) taking into account the mechanical error of the tab 20 indicated by the alternate long and short dash line, diagonally right from the center position It bends up and a valley 121b is formed. When arranged in the same manner as the bus bar electrode on the front surface side, it extends beyond the range of the alternate long and short dash line and further extends in the diagonally right direction from the valley 121b to bend and form a diagonal 121a 'symmetrical to the valley 121b. It extends to the center part beyond the chain line.

  In this embodiment, as shown in FIG. 4, the crest 121 a ′ is at a position deviated upward in the figure from the range (b in the figure) in consideration of the mechanical error of the tab 20. Therefore, in this embodiment, the peak 121a having the same shape as the peak 121a ′ is moved in the direction of the arrow in the figure, and the peak 121a is arranged in the upward direction in the figure from the end indicated by the lower one-dot chain line. It is. As described above, the peak portions 121a and the valley portions 121b are alternately arranged without being connected to each other within the range b determined in consideration of the mechanical error with respect to the bus bar electrode 111 on the front surface side. The bus bar electrode 121 on the back surface side is disposed with a predetermined interval without overlapping with the bus bar electrode 111.

  The back electrode 12 including the bus bar electrode 121 and the finger electrode 120 including the peak portion 121a and the valley portion 121b is, for example, screen-printed with a silver paste at a temperature of several hundreds of degrees like the front electrode 11. It is formed by curing.

  With this configuration, as shown in FIG. 5, even when misalignment occurs during printing when forming the bus bar electrodes 111 and 121, a predetermined interval is formed in advance between the two. The shear stress based on the bus bar electrodes 111 and 121 due to pressurization at the time of connection of 20 is reduced. As a result, the concentration of shear stress is eliminated, and cracking of the solar cell 1 can be prevented.

  As described above, in this embodiment, the number of finger electrodes 110 of the front surface electrode 11 is made smaller than the number of finger electrodes 120 of the back surface electrode 12. Thus, since the quantity of the light which injects into the surface of the solar cell 1 can be increased by reducing the number of the surface electrodes 11, a solar cell characteristic can be improved.

  Moreover, by making the thickness of the finger electrode 110 of the front electrode 11 larger than the thickness of the finger electrode 120 of the back electrode 12, the resistance of the front electrode 11 can be reduced, and further the solar cell characteristics can be improved. .

  Next, a solar cell module according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a plan view showing a solar cell in a solar cell module according to the second embodiment of the present invention, where (a) is a light receiving surface (front surface) side and (b) is viewed from the back surface side. . FIG. 7 is a plan view showing the main part of the solar cell in the solar cell module according to the second embodiment of the present invention. FIG. 8 shows the solar cell module according to the second embodiment of the present invention. It is sectional drawing to which the principal part of the AA 'line cross section of was expanded.

  In the first embodiment described above, the peak 121a and the valley 121b of the bus bar electrode 121 are formed apart from each other. On the other hand, in the second embodiment, in order to reduce the resistance of the distant portion, a connection portion 121c that connects the peak portion 121a and the valley portion 121b is provided in a part of the finger electrode 120. It is. Since other configurations are the same as those of the first embodiment, the description thereof is omitted here.

  By providing the connection portion 121c, the resistance component as the bus bar electrode 121 can be reduced as compared with the first embodiment.

  And in this 2nd Embodiment, the connection part 121c is provided also in the location where the finger electrodes 110 and 120 of front and back overlap. These connecting portions 121c are wider than the finger electrodes, and even if printing misalignment occurs between the front and back finger electrodes 110 and 120, the connecting portions 121c and the front-side finger electrodes 110 overlap each other. Is formed.

  As shown in FIGS. 6 and 8, the connection portion 121 c of the bus bar electrode 121 exists on the back surface side of the surface electrode 11 where the tab 20 is disposed, at a position opposite to the finger electrode 110. The pressure applied at the time of tab connection is received by the connection part 121c. As a result, the concentration of shear stress is eliminated, and cracking of the solar cell 1 can be prevented.

  Next, a method for manufacturing a solar cell module using the above-described solar cell 1 will be described. In the solar cell module, as shown in FIGS. 1 to 3, a tab 20 as a wiring member is electrically connected to the front electrode 11 and the back electrode 12. In order to connect the tab 20 to the front electrode 11 and the back electrode 12, the conductive adhesive film 5 is used. First, the conductive adhesive film 5 is pressure-bonded at a position where the tab 20 is bonded. As the conductive adhesive film 5 to be crimped, a film having the same width as that of the tab 20 to be connected or a slightly narrower width is used. For example, if the width of the tab 20 is 0.5 mm to 3 mm, the width of the conductive adhesive film 5 is also 0.5 mm to 3 mm corresponding to the width of the tab 20. In this embodiment, as shown in FIG. 1, three tabs 20 having a width of 1.2 mm are used. For this reason, three conductive adhesive films 5 having a width corresponding to the width of the tab 20 are attached on the bus bar electrodes 111 and 121 of the solar cell 1 at a position where the tab 20 is bonded.

  The tab 20 is composed of a copper thin plate 20a, and the surface of the tab may be coated with tin, solder, or the like. In this embodiment, a coating layer 20b plated with tin is provided. The coating layer 20b constitutes a soft conductor layer. Although it has been described that tin is used for this coating layer, a conductive material that is softer than the finger electrodes 110 and 120 and the bus bar electrodes 111 and 121 and that softens at a temperature at which the adhesive layer of the conductive adhesive film 5 is cured is used. desirable. Soft conductive metals can be used, including eutectic solder with a reduced melting point.

  The tab 20 is pressed against the conductive adhesive film 5, heat treatment is performed while pressing, and the adhesive layer of the conductive adhesive film 5 is thermally cured to connect the tab 20 to the front electrode 11 and the back electrode 12.

  As the resin adhesive film 5, for example, a conductive adhesive film is used. The conductive adhesive film 5 includes at least a resin adhesive component and conductive particles dispersed therein. A resin adhesive component in which conductive particles are dispersed is provided on a base film made of polyimide or the like. The resin adhesive component is composed of a composition containing a thermosetting resin. For example, an epoxy resin, a phenoxy resin, an acrylic resin, a polyimide resin, a polyamide resin, a polycarbonate resin, a urethane resin, or the like can be used. These thermosetting resins are used singly or in combination of two or more, and one or more thermosetting resins selected from the group consisting of epoxy resins, phenoxy resins and acrylic resins are preferable.

  Examples of the conductive particles include metal particles such as gold particles, silver particles, copper particles, and nickel particles, or conductive or insulating core particles such as gold plating particles, copper plating particles, and nickel plating particles. Conductive particles formed by coating with a conductive layer such as a layer are used.

  In order to electrically connect each of the plurality of solar cells 1 to another solar cell 1 adjacent to each other by the tab 20, one end side of the tab 20 is connected to the surface electrode 11 on the upper surface side of the predetermined solar cell 1. At the same time, the tabs 20 are respectively attached to the conductive adhesive films 5 attached to the front and back of the solar cell 1 so that the other end side is connected to the back electrode 12 on the lower surface side of another solar cell adjacent to the predetermined solar cell 1. Put.

  As shown in FIG. 10, for example, the solar cell 1 placed on the hot plate is pressed using a heater block at a pressure of about 3 MPa, for example, and the tabs 20 are pressed against the solar cell 1 side. In FIG. 10, the conductive adhesive film is not shown. Then, the temperature of the heater block and the hot plate is heated at a high temperature at which the resin adhesive component is thermally cured, for example, heated to a temperature of 120 ° C. or higher and 200 ° C. or lower to fix the tab 20 by pressure and fix the tab 20. The solar cells 1 are electrically connected and arranged.

  In the above-described embodiment, a conductive resin film is used as the resin film, but a resin film that does not include conductive particles can also be used. In the case of using a resin adhesive that does not include conductive particles, electrical connection is performed by bringing a part of the surface of the back electrodes 11 and 12 into direct contact with the surface of the tab 20. In this case, the tab 20 is formed by forming a conductive film softer than the electrodes 11 and 12 such as tin (Sn) or solder on the surface of a conductor such as a copper foil plate, and a part of the surface electrode 11 and the back electrode 12. It is preferable that the connection is made so as to be embedded in the conductive film.

  Thus, what connected the some solar cell 1 by the tab 20 between the surface member 41 which consists of glass, and the back surface member 42 which consists of members, such as a weather-resistant film or glass, a plastic, etc. They are sandwiched between light-transmitting sealing materials 43 and overlapped. And the solar cell module shown in FIG. 6 is obtained by sealing the solar cell 1 with the sealing material sheet 43 between the surface member 41 and the back surface member 42 with a laminating apparatus.

  The solar cell module is fitted into an outer frame made of aluminum or the like using a sealing material on the outer periphery as necessary. The outer frame is formed of aluminum, stainless steel, a steel plate roll forming material, or the like. A terminal box (not shown) is provided, for example, on the surface of the back member 42 as necessary.

  FIG. 5 is an enlarged view of a main part of the solar cell taken along the line A-A ′, and FIG. 10 is a schematic view of a step of connecting the tabs.

  In the solar cell module according to the above-described embodiment of the present invention, the front-side bus bar electrode 111 and the rear-side bus bar electrode 121 do not overlap each other, and a large shear stress does not occur even when a misalignment occurs when both are formed. In this way, the positional relationship between the two is formed so as to be separated by a predetermined range.

  As described above, in the embodiment of the present invention, the peak portions 121a and the valley portions 121b are alternately arranged with respect to the bus bar electrode 111 on the front surface side without being connected to each other. For this reason, even if a mechanical error occurs, the front-side bus bar electrode 111 and the rear-side bus bar electrode 121 are spaced apart so that shear stress does not concentrate. Thereby, the malfunction of a solar cell module can be eliminated by generation | occurrence | production of the crack of the solar cell 1 at the time of crimping | compression-bonding.

  In the above-described embodiment, the bus bar electrodes 121 on the back surface side are alternately arranged without the mountain portions 121a and the valley portions 121b being connected to each other, but the bus bar electrodes 121 on the back surface side are formed in a continuous polygonal line shape. In addition, the bus bar electrodes 111 on the front surface side may be alternately arranged so that the crests and troughs are not connected to each other.

  Further, in the above-described embodiment, an example in which three tabs 20 are connected on the solar cell 1 has been described. However, the number of tabs 20 is not limited to three, and also when two or more tabs 20 are used. The present invention can be applied.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims for patent.

DESCRIPTION OF SYMBOLS 1 Solar cell 110 Finger electrode 111 Bus-bar electrode 120 Finger electrode 121 Bus-bar electrode 120a Mountain part 120b Valley part 121c Connection part 20 Tab

Claims (4)

In a solar cell module comprising a front surface side protection member, a back surface side protection member, and a plurality of solar cells connected to each other by a wiring member between the front surface side protection member and the back surface side protection member,
The solar cell is provided on a light receiving surface, and is connected to the wiring member with a plurality of front surface side finger electrodes and bus bar electrodes, and is provided on the back surface with a plurality of back surface side finger electrodes connected to the wiring member and A bus bar electrode,
Either one of the bus bar electrodes is arranged such that the peak portions and the valley portions are not alternately connected to each other, and is not overlapped with the other bus bar electrode, and is arranged with a predetermined interval. module.   The back side bus bar electrodes are arranged in a range determined in consideration of mechanical errors with respect to the front side bus bar electrodes, without alternately connecting peaks and troughs to each other. The solar cell module according to claim 1.   3. The solar cell module according to claim 1, wherein a connection portion that connects the peak portion and the valley portion is provided in a part of the finger electrode.   The solar cell module according to claim 3, wherein the connecting portion is formed wider than the finger electrode.

Images